A large increase in protein synthesis in myelin has been observed in animals demyelinating as a result of edema from chronic triethyl tin (TET) administration. The mechanism of this increase will be examined in cell-free systems. Microsomes, polyribosomes, and pH 5 enzymes will be prepared by methods described by Zomzely-Neurath from normal and TET rats. Various components will be cross-incubated to determine the site of the increased activity, i.e., normal microsomes or polyribosomes with TET pH 5 enzymes, etc. Rat central nervous tissue demyelinating as a result of edema from TET administration do not show any increase in degradative enzymes, although such enzymes are present in experimental allergic encephalomyelitis. The possibility will be explored that swollen myelin in TET edema may be more susceptible to enzymatic activity normally present because of its open structure. Various proteolytic enzymes such as trypsin, pronase, carboxypeptidase, and snake venon enzymes will be incubated with normal and edematous myelin to compare the extent of breakdown. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate will be used to monitor the enzymatic activity on myelin to visualize whether certain myelin proteins are more vulnerable to breakdown than others.